The present invention broadly relates to the papermaking art and, more specifically, concerns a new and improved construction of a longitudinal wire papermaking machine.
Generally speaking, the longitudinal wire papermaking machine of the present development is of the type comprising a movable longitudinal wire and a headbox coacting therewith for the infeed of a fiber stock suspension or the like to a pre-dewatering path or zone. This pre-dewatering path is formed by a substantially horizontally extending, essentially planar section or portion of the longitudinal wire. The longitudinal wire is guided at a dewatering region following this wire section, viewed with respect to the direction of movement of the longitudinal wire, downwardly over a convex domed first deflection element and thereafter upwardly along a downwardly domed guide surface of a dewatering element, which is water pervious at least over a portion of its curved extent or course, towards an upwardly domed second deflection element. The longitudinal wire travels forwardly of the first deflection element and after the second deflection element essentially in the same wire plane.
A papermaking machine of this type has been disclosed in the commonly assigned, U.S. application Ser. No. 06/321,677, filed Nov. 16, 1981, now U.S. Pat. No. 4,417,950. With the papermaking machine described in the aforementioned application the longitudinal wire, together with an additional upper wire, is guided out of the wire plane over a guide shoe and a first deflection cylinder at the dewatering region or zone. The fiber stock suspension is dewatered upwardly already at the region of the wire plane through both of the wires which contact one another at the region of the wire plane. The resultant filtered or expressed water is removed by a catch basin or container which must be arranged between the first deflection cylinder and the dewatering roll which immerses or extends beneath the wire plane. With this arrangement, with predetermined dimensions of the dewatering region, the mounting space available for the dewatering element, which is to be designed in consideration of the largest possible wrap angle, is limited by the mounting space needed for the placement of the catch basin or container.